1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
ad-work [718]
3 years ago
14

The effectiveness of two types of textbook is compared. A class of 30 students is randomly divided into two groups. One group us

es digital textbooks and the other group uses paper textbooks. A summary of their test scores at the end of the session is given below. Digital Textbook: Paper Textbook: Construct a 90% confidence interval for the difference in scores between the two groups assuming underlying normal distributions with equal variance. Find the lower bound of the confidence interval (round off to first decimal place).
Mathematics
1 answer:
Gnoma [55]3 years ago
7 0

Answer:

- 18.377

Step-by-step explanation:

n1 = 17 ; xbar1 = 78.4 ; s1² = 90.3

n2 = 13 ; x2bar = 92 ; s2² = 107.8

Confidence interval :

(x1 - x2) ± Tcritical * sqrt[(sp²/n1 + sp²/n2)]

Pooled variance = Sp² = (df1*s1² + df2*s2²) ÷ (n1 + n2 - 2)

df = n - 1

Sp² = (16*90.3 + 12*107.8) / 28

Sp² = 97.8

Tcritical, 90%, df = n1 + n2 - 2 = 28 (1 - tail)

Tcritical = 1.313

(78.4-92)±1.313*sqrt[(sp²/n1 + sp²/n2)]

Margin of Error = Tcritical * sqrt[(sp²/n1 + sp²/n2)] Margin of Error = (1.313 * √(97.8/17 + 97.8/13)) = 4.7771473

Lower boundary :

(78.4-92) - 4.7771473

-13.6 - 4.7771473

= −18.3771473

= - 18.377

You might be interested in
What is the distance from the school to the theater?
defon
The "horizontal" distance is 8-2 = 6.
The "vertical" distance is 7-3 = 4.
The Pythagorean theorem tells you the straight line distance is then
  √(6² + 4²) = √52 = 2√13 ≈ 7.21
8 0
4 years ago
The elevator of a high-rise office building provides access to all floors. if each floor is 5 meters high and the elevator trave
nadya68 [22]
Height of each floor = 5 meters
time to travel from the first floor to 68th floor = ?
Speed of elevator = 7.5m/s
While an elevator travels from 1st floor to 68th floor, we will multiply the height of floor with 67 to get the distance covered by the elevator form 1st floor to 68th floor, the height of 68th floor will not be counted in the distance because an elevator reaches the 68th floor not covered the height of that floor.
Distance = 5 x 67 = 335m
Now calculate the time by using the formula;
time = distance / speed
= 335m / 7.5m/s
= 44.667 seconds
Thus, an elevator will take 44.667 seconds to reach 68th floor.

6 0
3 years ago
(Distance Formula)<br> What is the distance between (-8, -1) and (-5, 3)?
eduard

Answer:

5

Step-by-step explanation:

4 0
3 years ago
Read 2 more answers
Which value, when placed in the box, would result in a system of equations with infinitely many solutions?
ira [324]
<span>For a system of equations to have infinitely many solutions, the equations have to be lineary dependent, (i.e. one of the equations is a multiple of the other equation). For the given equation to have infinitely many solutions, the second equation have to be a multiple of the first equation. The first equation can be rewritten as y - 2x = -5 The second equation is the first equation multiplied by 2, i.e. 2(y - 2x= -5) = 2y - 4x = -10 Therefore, the correct answer is -10 (option a).</span>
7 0
3 years ago
Read 2 more answers
Today the 6th graders had 5 students absent, the 7th graders had 8 students absent,and the 8th graders had 9 students absent. If
Irina18 [472]
All you have to do is multiply 8 by 20 which is 160
7 0
3 years ago
Other questions:
  • Dave earns $150.00 per week plus 3.8% commission. He sold $4175.68 in the month of February. What is his gross monthly earning f
    14·1 answer
  • In a family with 7 children, excluding multiple births, what is the probability of having exactly 2 girls? Assume that having a
    15·1 answer
  • Which polynomial represents the algebra tile configuration shown?
    13·3 answers
  • Greg's soccer team is selling sets of 3 raffle tickets for $5.00. What is the constant of proportionality of dollars per ticket?
    8·2 answers
  • A bag contains 14 gray 7 black and 10 white marbles. A marble is drawn at random what is the thecorical probability as a decimal
    15·1 answer
  • Clark plans to fertilize his yard this summer. His yard is 40 feet wide a 60 feet long. thus included a 4 foot wide and 20 foot
    13·2 answers
  • Evaluate 24 + 24 ÷ 6
    9·2 answers
  • Please help marking brainlists 5-9c-4c=
    13·1 answer
  • (8.02) An archaeological dig turns up large numbers of pottery shards, broken stone implements, and other artifacts. Students wo
    12·1 answer
  • What two numbers multiplied equal 8 but added get -7?
    14·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!